python 操作 mysql

1.pymysql
2.ORM框架SQLAlchemy

一、python原有模块 pymysql

安装
pip install pymysql
使用

import pymysqlconn = pymysql.connect(host='',port = 3306,user ='',passwd='',db='',)cursor = conn.cursor()cursor = conn.cursor(cursor=pymysql.cursor.DictCursor)effect_row = conn.execute('sql','argv')conn.commit()newid = conn.lastrowidrow1 = conn.fetchonerow2 = conn.fetchmany(n)row3 = conn.fetchall()cursor.scroll(n,'absolute')cursor.scroll(n,'relative')cursor.close()conn.close()

二、ORM框架SQLAlchemy
安装
pip install SQLAlchemy
使用
1.创建engine，使用ConnectionPooling 连接数据库，使用 Dialect执行sql

form sqlalchemy import create_engineengine = create_engine('mysql+pymysql://user:pass@host:port/dbname?charset =utf8',max_overflow=5)                      ('mysql+mysqldb://user:password@host:port/dbname')                   ('mysql+mysqlconnector://user:password@host:port/dbname')                 ('oracle+cx_oracle://user:pass@host:port/dbname')cursor = engine.execute('sql',[(**args),()])cursor.fetchonecursor.fetchmany()cursor.fetchall

2.ORM使用

from sqlalchemy.ext.declarative import declarative_basefrom sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index  #(列，整数，字符串，外键，唯一索引，索引)from sqlalchemy.orm import sessionmaker, relationshipfrom sqlalchemy import create_engineengine = create_engine('mysql+pymysql://user:pass@host:port/dbname',max_overflow=5)Base = declarative_base()

#创建表class table(Base):    __tablename__ = 'users'    id = Column(Integer, primary_key=True, autoincrement=True)    name = Column(String(32),default='red', unique=True)    extra = Column(String(16),index=True, nullable=True,ForeignKey("favor.nid"))    __table_args__ = (    UniqueConstraint('id', 'name', name='uix_id_name'),    Index('uix_id_name', 'name', 'extra'),    )def init_db():    Base.metadata.create_all(engine)def drop_db():    Base.metadata.drop_all(engine)Session = sessionmaker(bind=engine)session = Session()#增删改查session.add(Users(name="alex0", extra='sb'))session.add_all([    Users(name="alex1", extra='sb'),    Users(name="alex2", extra='sb'),])session.query(Users).filter(Users.id > 2).delete()session.query(Users).filter(Users.id > 2).update({"name" : "099"})session.query(Users).filter(Users.id > 2).update({Users.name: Users.name + "099"}, synchronize_session=False)session.query(Users).filter(Users.id > 2).update({"num": Users.num + 1}, synchronize_session="evaluate")session.commit()ret = session.query(Users).all()ret = session.query(Users.name, Users.extra).all()ret = session.query(Users).filter_by(name='alex').all()ret = session.query(Users).filter_by(name='alex').first()ret = session.query(Users).filter(text("id<:value and name=:name")).params(value=224, name='fred').order_by(User.id).all()ret = session.query(Users).from_statement(text("SELECT * FROM users where name=:name")).params(name='ed').all()#　条件ret = session.query(Users).filter_by(name='alex').all()ret = session.query(Users).filter(Users.id > 1, Users.name == 'eric').all()ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == 'eric').all()ret = session.query(Users).filter(Users.id.in_([1,3,4])).all()ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all()ret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name='eric'))).all()from sqlalchemy import and_, or_ret = session.query(Users).filter(and_(Users.id > 3, Users.name == 'eric')).all()ret = session.query(Users).filter(or_(Users.id < 2, Users.name == 'eric')).all()ret = session.query(Users).filter(    or_(        Users.id < 2,        and_(Users.name == 'eric', Users.id > 3),        Users.extra != ""    )).all()# 通配符ret = session.query(Users).filter(Users.name.like('e%')).all()ret = session.query(Users).filter(~Users.name.like('e%')).all()# 限制ret = session.query(Users)[1:2]# 排序ret = session.query(Users).order_by(Users.name.desc()).all()ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all()# 分组from sqlalchemy.sql import funcret = session.query(Users).group_by(Users.extra).all()ret = session.query(    func.max(Users.id),    func.sum(Users.id),    func.min(Users.id)).group_by(Users.name).all()ret = session.query(    func.max(Users.id),    func.sum(Users.id),    func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all()# 连表ret = session.query(Users, Favor).filter(Users.id == Favor.nid).all()ret = session.query(Person).join(Favor).all()ret = session.query(Person).join(Favor, isouter=True).all()# 组合q1 = session.query(Users.name).filter(Users.id > 2)q2 = session.query(Favor.caption).filter(Favor.nid < 2)ret = q1.union(q2).all()q1 = session.query(Users.name).filter(Users.id > 2)q2 = session.query(Favor.caption).filter(Favor.nid < 2)ret = q1.union_all(q2).all()